BR112016011437B1 - PROCESS AND DEVICE FOR TREATMENT AND PROCESSING OF SLUDGE AND SOLIDIFIED ORGANIC SLUDGE CAKE - Google Patents

Abstract

PROCESS AND DEVICE FOR THE TREATMENT OF LIQUID SLUDGE AND SLUDGE CAKES OBTAINED WITH THIS PROCESS. The present invention relates to a process, a device (1) for the treatment and conditioning of liquid sludge (2), and a cake of solidified sludge obtained with this process, in which a first emulsion (14) of sludge in a container (5, 6) in-line fed at a first flow rate Q (m3/h), by shocking the slurry with air (13) injected into the container at a flow rate Q'(Nm3/h), where Q' (greater than) 5Q, in a first zone (8) of small volume less than 0.05 m3, to create the first emulsion (14) which is then conveyed in a second zone (16) of the container that extends in a first determined length L1, then evacuated via an element that generates a pressure drop (18) in a compartment (19) which extends over a second determined length L2. At least one flocculant (22) is injected to obtain a second coagulated emulsion (23) which is degassed at least in part, then the suspended matter of the second emulsion (23) thus obtained is filtered or allowed to settle.

Description

[0001] The present invention relates to a process for treating sludge by injecting air into a slurry stream.

[0002] It also refers to a sludge treatment device, applying this process and the sludge cakes obtained with it.

[0003] The invention finds a particularly important application, although not exclusive in the field of thickening and/or reducing the volume of sludge from a water treatment and/or accumulated in industrial water settling basins.

[0004] Sludge thickenings are known (FR 2 729 383), allowing to improve the sicity of compact sludges, thanks to mechanical scrapers that move over the permeable bottom of storage tanks.

[0005] These devices carry risks of clogging that require declogging means and present the weaknesses of mechanical equipment.

[0006] There are also known processes for thickening sludge from water treatment by flocculation/decantation that require a surface degassing, the injection of a refloculation reagent into the sludge and finally a thickening in at least one lamellar thickener. In this case, the thickening is mechanically foreseen and cannot avoid frequent clogging.

[0007] It is also known systems of exhaustion tables that present, however, important difficulties of operation, and need the installations of considerable size.

[0008] Mechanical thickening systems of the rotating drum type are also known.

[0009] These are robust systems, but limited in terms of results, as they do not allow to expect thickening greater than 30 to 40 g/l of DM.

[0010] Static thickening systems formed by settling tanks are also known.

[0011] In case of static thickening, residence times are, however, considerable and unfortunately generate anaerobic evolution of the sludge, causing nauseating odors and an increase in the colloidal character of said sludge.

[0012] It is also known (FR 2 966 818) a process for dereferencing sludge by injecting air into a slurry stream, the efficiency of which can be further improved.

[0013] The present invention aims to provide a process and a device, responding better than those previously known to the requirements of practice, notably by not using mechanical systems capable of seizing or systems that generate a structural modification of the sludge to treat, but hydraulic systems, as well as inexpensive reagents (compressed or super-pressed air or classic flocculant), and this allows a quick decontamination of the sludge, the use of the thickening process, according to the invention, requiring only a few seconds or minutes.

[0014] To do this, the invention starts from the principle of a continuous or semi-continuous treatment and/or thickening (by alternative batch) of a sludge, in which the sludge is fed into a compartment with continuous flow, injecting there simultaneously the air with an important flow (several tens, even hundreds of Nm3/h) causing velocities V of the emulsion obtained important at the place where the air and the mud meet (V > 10m/s) (for example, 50m/s) , the emulsion being formed from a multitude of sludge droplets in the strong air current, a pressure loss determined in the emulsion is created by narrowing in and/or at the exit of the compartment, if a flocculant is injected, after this narrowing, it is degassed the said emulsion at atmospheric pressure and the whole is recovered in a filtering or settling device.

[0015] Advantageously, the sludge is also rapidly concentrated downstream in a container with a spillway.

[0016] For said purpose, the invention notably proposes a process for treating and processing sludge, in which a first sludge emulsion is created in a pressurized in-line container fed by the slurry continuously at a first flow rate Q (m3/h ), by collision of the mud with the air injected into the container at a flow rate Q' (Nm3/h), with Q' > 5Q, then it is evacuated at the container exit, via an element that generates a loss of head, before recovery of the emulsion and degassing, then the suspended matter of the emulsion thus obtained is filtered or allowed to decant, separating them from the liquid part that empties continuously, characterized by the fact that the mud and air are injected into a first area of the container. , then the emulsion thus formed is evacuated to a second zone of the container which extends over a first determined length Li, the injection of air and sludge in the first zone and length L1 being suitable for constituting said first formed emulsion of droplet those of mud in the air, because the evacuation is carried out in a compartment that extends over a second determined length L2, into which at least one flocculant is injected, in order to obtain in said compartment a second air emulsion in the coagulated mud and flocculated, and by the fact that said second emulsion is degassed at least in part by ventilation of the compartment.

[0017] Advantageously, the first zone is a small volume, notably confined between two side walls (as in a venturi or a pipe restriction, for example), and, for example, less than 0.005 m3.

[0018] By semi-continuous, it is understood by successive batches, which are replaced one after the other in the air, or substantially without stopping, to allow continuous or semi-continuous treatment, allowing an excellent cadence since then.

[0019] It is observed in the case that the first emulsion is first of all a mud emulsion. It is understood as an emulsion where the slurry is in the dispersed phase in the air, which is the continuous phase.

[0020] The second emulsion is, on the contrary, first of all an emulsion of gas in the slurry, the flocculant having blocked micro and millimeter gas bubbles in the middle of the slurry flakes.

[0021] The particularly small size of the injection zone (eg 0.01 m3) will allow for an excellent mix/air.

[0022] In fact, there is in that place a zone of high velocity, causing kinetic shocks, which allows the mud to explode in the gas. The emulsion thus obtained then passes into the second zone of the container which extends over a certain length.

[0023] It should be noted that the first and second zones can be separated by a restriction (a venturi and/or an orifice), forming the two zones in two separate chambers.

[0024] This length necessarily entails, even if it is slight, a gradient of depression towards the exit of the container which turns out to allow an agglomeration, coagulation, compaction of the sludge, thus preparing the first emulsion thus modified for the treatment that follows.

[0025] Advantageously, the first determined length Li is greater than 50 centimeters, eg greater than 1 m, eg 1 m 50.

[0026] Thus, a pressure/depression sequence is carried out which, surprisingly, creates a state of matter (emulsion), allowing to obtain in fine a superior physicality gain.

[0027] In particular, the pressure takes an energy capable of destabilizing and breaking the electrostatic bonds (Coulombian type) or dipolar (Van des waals type) and thus make water leave the organic fractions.

[0028] The dispersion that follows produces, as for it, an acceleration movement of the sludge and an expansion or stretching towards the zone of lower pressure, continuing the destabilization and destructuring effect of the colloids and an effect of breaking the connections.

[0029] Eventually, and in advantageous embodiments, compression sequences are reiterated again, then depression ... to prolong, simplify/produce the effects sought.

[0030] In this case, the technical effect, obtained by the invention, is above all linked to the porosification of the sludge obtained, thanks to the collision of the slurry with the air in the conditions of dimensions and active zones of the reactor, after the pressure drop between container and compartment that will be sized more precisely and naturally by the technician, depending on the treated effluent, the flow rates used and the flocculant used.

[0031] The air is introduced into the mud flow, thus causing a shock between the air and the mud, then pressure differentials, for example, as will be seen by a venturi system with air suction.

Advantageously, the second determined length L2 is greater than 1 m, more advantageously greater than 2 m or 3 m, for example 5 m or more.

[0033] In advantageous embodiments, one and/or the other of the following provisions are also used: - the mean pressure P in the container is such that 150 kPa (1.5 bar) < P < 1000 kPa (10 bar) and Q' is such that 10 Q < Q' < 100 Q, eg Q'> 50 Q; - the emulsion is greatly degassed at the exit of the container, for example, inside a degassing chamber equipped with a mixing medium; - the in-line container is a column with an average diameter of height H > 10 d, the sludge being introduced at the bottom of the column in the gaseous layer created by the air injected at the level of said slurry feed (for example, above or below ); - the slurry is projected in the column onto a wall or an internal screen of the container to improve its breakage in the gaseous flow. To do this, the outlet in the slurry feed container is advantageously located facing a wall and/or the screen, at a small distance, for example less than 5 cm; - the slurry is introduced into the lower part of the container via a static mixer. A static mixer is a system known per se not supplied with energy, situated in the slurry feed tube and comprising, for example, static mixing slurries and/or oblique diaphragms, etc...; - flocculant is a polymer injected at the immediate exit of the container, before ventilation. It is, for example, an organic flocculant of the cationic type; - upstream of the container is introduced into the sludge flow, at least one reagent selected from sand, calcium carbonate, burnt lime, oxidation reagents and/or coagulation auxiliary reagents; - at least one reagent selected from sand, calcium carbonate, burnt lime, oxidation reagents and/or reagents auxiliary to coagulation is introduced downstream of the container; - the compartment is tubular with an average flow cross section equivalent to that of the container; - the tubular compartment comprises at least one element that generates a pressure drop downstream of the container outlet, at the outlet of which the flocculant is injected; - the tubular compartment comprises at least one second element which generates a pressure drop upstream of the first generating element, at the outlet of which at least one reactant and/or air are introduced; - the element(s) that generate pressure drop are Venturi tubes; - a rapid and/or appreciably instantaneous concentration (a few seconds or even minutes, for example, seven to ten minutes) of sludge is carried out by flotation/accumulation of the flocculated emulsion in a capacity, which acts as a concentrator, the concentrated sludge being evacuated in continuous, for example, by overflow.

[0034] Surprisingly, the important volumes of insufflated air actually generated a sludge mixed with very thick air bubbles (> several millimeters) that considerably increases the ascent speeds of the blades during flotation (observed ascent speed multiplied by a factor of ten, even more).

[0035] Advantageously, by filling more or less the capacity surface, it is possible to regulate (depending on the air flows and sludge used) the thickness of the floating layer, which can then and, furthermore, accumulate due to its weight, allowing concentrations of 100 to 120 g/l of DM to be obtained, knowing that the quality and transparency of the water obtained under the flocculated sludge always remains exceptional (DCO less than 200 mg/l, even 100 mg/l, in the case of biological sludge); - a complementary treatment of the sludge is carried out downstream of the tubular compartment by centrifugation, filtration and/or pressing; - the injected air is heated and/or mixed with water vapor; - the air is injected against the mud flow or to form a helical flow eventually against the mud flow counter current or injected at right angles to the mud flow, or in the direction of the mud flow.

[0036] The invention also proposes a device that applies the process as described above.

[0037] She proposes, on the other hand, a Device for the treatment and processing of sludge that comprises an in-line container, means for feeding sludge from said container in continuous at a first flow rate Q (m3/h), means for feeding the said container with air at a flow rate Q' (Nm3/h), with Q' > 5Q, and means for filtering and/or decanting the emulsion, thus flocculated, adjusted to separate the liquid part from the suspended matter and recover it in continuous, characterized in that the slurry and air feed means of the vessel are adjusted to inject the slurry and air into a first zone of the vessel, then to convey the mixture in a first length Li to form a first drop emulsion. of sludge in the air, in that it comprises an evacuation compartment of the first emulsion obtained in the container, the compartment being tubular extending over a determined length L2, comprising ventilation means and injection means of at least one f loculant in said tubular compartment upstream with respect to said vent, so as to form a second air emulsion in the coagulated and flocculated sludge.

[0038] By determined length Li or L2, it is necessary to understand a distance greater than 0.5 m, advantageously 1 m, for example 2 m, 3 m and advantageously i0 m.

[0039] Advantageously, the first zone of the container has a small volume of less than 0.05 m3, notably confined between two side walls (smaller section) (between which the mud is therefore introduced to exit towards the second zone of larger volume and/or wider section).

[0040] The smaller volume is, for example, formed by a venturi and/or is part of injection means or a device for simultaneous injection of air and mud.

[0041] Advantageously, the in-line container is a column of average diameter of height H > 10 d, the sludge being introduced in the lower part of the column in the gaseous layer created by the air injected into the level, for example, a little below or a just above (one or a few centimeters) of said mud feed.

[0042] Also, advantageously, the column still comprises an internal screen arranged at the outlet of the injection means in the column, for breaking the mud jet.

[0043] Still advantageously, the device comprises a static mixer of the sludge upstream of the container.

[0044] Advantageously, the compartment comprises at least one element that generates pressure drop, for example, a venturi.

[0045] In an advantageous embodiment, the invention further proposes a degassing chamber equipped with mixing means located downstream of the container.

[0046] Advantageously, a capacity is also provided at the outlet or downstream of the compartment, playing the role of a concentrator arranged to allow the flotation of the flocculated sludge at a certain height (in a determined range, for example, between 20 centimeters and 1 meter mud thickness), provided with means of continuous mud evacuation by overflow.

[0047] The invention also proposes a cake of solidified sludge obtained from an organic sludge of equal or similar porosity to that of pumice. By equal or similar, it is understood a porosity Φ = V pores/V total equal to + 20%, advantageously + 10%.

[0048] The porosity is, for example, calculated, in a way known per se, on prepared samples, after extracting the sample fluids with, for example, an extractor known under the name Soxhlet or by vacuum distillation. The total volume V is measured, for example, by measurement, then the solid volume, for example, with a pycnometer.

[0049] The porosity of the pumice stone is in the order of 85% (+ 5%).

[0050] Advantageously, the volumetric mass of the cake is, for example, comprised between 0.5 and 0.9 g/cm3.

Advantageously, the cake is obtained by the process and/or the device as described above.

[0052] The invention will be better understood by reading the following description of embodiments given below by way of non-limiting examples. The description refers to the accompanying drawings, in which: figure 1 represents a diagram illustrating a first embodiment of a device that applies the method, according to the invention; figure 2 represents a diagram illustrating a second embodiment of a device according to the invention; figure 3 represents an operating diagram of a third embodiment of a device according to the invention; figure 4 schematically shows a fourth embodiment according to the invention with degasser and concentrator; figures 5A, 5B and 5C represent front, side and top views of a device according to a fifth embodiment of the invention; Figure 6 represents a partial side view of a device according to a sixth embodiment of the invention; Figures 7A, 7B and 7C are respectively a top view and side sectional views of the concentrator of Figure 5; figures 8A and 8B represent top and side sectional views of a concentrator, according to another embodiment; Figure 9 is a view, in perspective (and in transparency) of another embodiment of a concentrator/float usable with the invention.

[0053] Figure 1 shows a device 1 for the treatment and processing of sludge, for example, pumped by a pump 3, from a reservoir 4 for storing the sludge, for example, contaminated, with high organic content and therefore , generators notably of ammonia (NH3).

[0054] The device comprises a container 5 formed by a tubular column 6 of diameter d, for example, comprised between 30 cm and 50 cm.

[0055] The slurry is injected at a flow rate Q, for example, of 20 m3/h through a penetrating pipe 7 (equipped with static mixing means not shown, such as a helical screw) in a first zone 8 located in the lower part 9 from column 6, of smaller volume, for example 10 liters. The volume of zone 8 is delimited by the part of the compartment situated in the volumetric extension of the end 10 of the penetrating pipe 7 and by the alternately wall 11, for example cylindrical, and situated 5 cm from said end 10.

[0056] The device 1 also comprises a supply 12 with air 13 at a flow rate Q’ (Nm3/h) from compartment 6, for example, below the supply with sludge (pipe 7). But air can also be fed in counter-flow of mud, for example via a 12’ helical internal ramp.

[0057] It is recalled, on the other hand, that the value of gas flows is classically given in Nm3/h (Normo-cubic meter/h), the volume (in Nm3/h) being, in this case, considered in its carried value at a pressure of one bar, a temperature of 20 oC and 0% humidity as this is naturally admitted and understood by the technician, engineer, in the field of chemical engineering.

[0058] The air is at overpressure P’ in relation to the average internal pressure of column 6 and is injected at a flow rate Q’ much higher than the mud flow, for example, 500 Nm3/h.

[0059] The meeting of air and mud creates a first mud emulsion 14, with mud breakage (drops 15 dispersed) in the air, which then rises in the full height column H, in a second zone 16 of a first length L1, before reaching the top 17 of the column which comprises an outlet element 18, for example a valve and/or a regulating valve, allowing a permanent overpressure of the first emulsion inside the compartment, for example, at a pressure average P of the order of 1.5 bar absolute, with a ΔP between the bottom 9 and the top 17 of the column of some millibarias.

[0060] According to the embodiment of the invention, described here, the device 1 also comprises a tubular compartment 19, for example, in diameter, such that ^ d < d' < d of evacuation of the first emulsion onto a second determined length L2, eg 3 m.

[0061] Compartment 19 comprises an outlet 20 for venting its contents, for example, at a distance L’2 = % L2 from the outlet of column 6.

[0062] Upstream of said outlet, the device 1 comprises means 21 known per se (metering pump, preparation container, etc.) for introducing, in compartment 19, a flocculant 22, located, for example, in the vicinity of the compartment (for example, 5 cm from element 18), for example, formed of a polymer of a known type, adapted by the technician according to the treated sludge.

[0063] This is followed by the formation of a second emulsion 23, the said time of gas in the flocculated sludge.

[0064] The tubular compartment allows a flow initially under overpressure, then gravity or substantially gravity (inclination a), once the emission ventilation operated by outlet 20.

[0065] A valve 24 makes it possible to regulate said ventilation if necessary.

[0066] The emulsion 23 then falls into reservoirs, in this case filter bags 25, 25’, allowing to recover the dehydrated sludge 26 that floats on the surface, the clear water 27 being recovered in the lower part. The mud cakes 28 extracted from the bags are then stocked and/or spread out. Surprisingly, they have no odor or a humus odor.

[0067] The separated water benefited from the same physicochemical treatment as the mud. The air was not trapped there, but its redox potential increased, the colloidal fractions being fixed in the OM, leaving a transparent water, charged in MES and, in organic matter, very weak. For example, you get a turbidity of 5 to 10 NTU, whereas with a band filter, you get much more turbid water, 25 to 35 NTU.

[0068] The filtrate is also less viscous than in the prior art, with equal initial slurry quality. A measurement of the CST gives in the case of the order of 5 seconds, whereas the previous technique obtains of the order of 10 s.

[0069] The DCO is also lowered to less than 100 mg O2/l for a biological sludge filtrate and to less than 200 mg/l for a digested sludge filtrate (for a filtrate of the same sludge obtained with a classic 1000 centrifuge at 3000 mgO2/1), as well as a MES content < 50 ppm to over 1000 ppm with the prior art under equivalent conditions.

[0070] Figure 2 shows another embodiment of a device 30, according to the invention, for treating sludge 31 introduced into an end part 32 of a container 33 elongated around an axis 34 and of height H determined, for example, 1 m.

[0071] The container is maintained at an average pressure P, for example, 2 bar absolute, and is formed by a cylinder of diameter d, for example, 300 mm.

[0072] The slurry feeds a reduced zone 35, for example of 10 liters situated at the end part 32 also fed at the end of the container and upstream of the introduction of the sludge by an air inlet 36, for example, at a pressure P ' > P, for example, 3 bar absolute.

[0073] The air is fed with a very strong flow Q’, for example, 100 Nm3/h, the sludge being introduced at a flow rate Q, for example, of 10 m3/h.

[0074] The slurry 31 explodes in the air that is under overpressure, a slight depression ΔP existing between the container at the arrival of the sludge at 35 and the exit of the sludge emulsion 37 downstream of the container.

[0075] At the outlet of the container 33 there is a venturi 38 and/or a regulation valve, generating a head loss, for example, of 0.4 bar, the mud emulsion being, in this case, evacuated into a tubular compartment 39 comprising a first cylindrical part 40 of diameter d' (for example, d' = d) which is at a pressure P1 < P, for example in the case of 1.6 bar (in the example considered), into which it can be injected , downstream of the venturi, and in close proximity to it (eg at 10 cm to allow for good mixing), a reagent at 41, and/or again air (instrument 42).

[0076] In said embodiment, the tubular housing also comprises a second cylindrical part 43, separated from the first part 40 by a second venturi 44, said second part being of diameter d'' with, for example, d'=d '' = d.

[0077] Downstream of the venturi 44, and close to it (1 to 10 cm), a supply 45 with flocculant is provided, with means known per se (metering pump, etc...) and an outlet 46 for ventilation and/ or an open sludge outlet 47 to the atmosphere, the pressure P2 in that second part therefore being very quickly brought to atmospheric pressure, for example, 1.3 bar at the venturi outlet to quickly pass to 1 bar = one atmosphere at the outlet 47, the emulsion becomes, after the addition of the flocculant, an air emulsion in the sludge flakes, which gravitately flow over the end.

[0078] The total length of compartment L2 ~ 1I + 12, is, for example, 10 m, with 11 = 3 m and 12 = 7 m, but other values are possible, the ratio between 11 and 12 being, in general, but not limiting, such that 11 < 12.

[0079] The device 30 further comprises a filter 48 and/or a settling tank for evacuating the purified water 49 in the lower part and the dewatered sludge 50 in the upper part.

[0080] A third embodiment of a device 51 according to the invention is shown in FIG.

[0081] The device 51 comprises a container 52 fed by an instrument 53 in the lower part and, with slurry, and under said instrument 53, fed with long air with strong flow by a second instrument 54.

[0082] More precisely, the container is formed by a vertical column 55 comprising a first part that forms a reservoir 56 of very violent mixing/mixing of air and slurry, of small dimensions, for example cylindrical of height h1 = 50 cm and diameter di 30 cm, is a volume of the order of 35 l, making it possible to obtain the first emulsion 57 of droplets 58 of broken mud.

[0083] This droplet emulsion in a strong upward flow of air at pressure then penetrates into a cylindrical conduit 59, extending the reservoir 56, of smaller diameter d2 < d1, for example, 10 cm in diameter and extending into a length h2, for example, of 1 m (with Li = hi + h2).

[0084] In this air column, the gaseous flow performs a stripping (stripping in Anglo-Saxon language) of the gases contained and/or coming from the sludge and notably the NH3 ammonia, performing, surprisingly and depending on the operating conditions, and treated organic sludge, an almost complete elimination of unwanted gases (< a few ppm) trapped in the sludge.

[0085] The length i2 is advantageously sized to do this by the technician.

[0086] At the top 60 of the compartment, an adjustment valve 6i and/or an evacuation valve is provided for a tubular compartment 62.

[0087] The pressure of the emulsion 57 goes from Pi (eg 3 bar), in the initial reservoir 56, to P2 (2.890 bar) a little lower than Pi in the upper part of column 59 of the vessel, at the valve level 61, with ΔP = P2 - Pi = some milibars, then at the valve outlet at P3 = 2 bar (due to pressure drop in the valve).

[0088] More precisely, compartment 62 comprises a first section 63 of length l3, for example, 5 m, which ends in a venturi 64 that passes the pressure P'3 < P3 at the end 65 of the first section at a pressure P4 in a second section 66 of the compartment in gravity inclination, provided with an outlet 67, section 66 being of length i4 , eg im, with L2 = i3 + i4.

[0089] The section 66 is connected to the filter 68 for separating the suspended matter 69 from the liquid part 70, which empties continuously in 7i, in a way known in itself.

[0090] The compartment comprises means 72 for feeding flocculant 73 from a reservoir 74 for preparation by mixing and mixing. A metering pump 75 carries the flocculant in the slurry emulsion exiting the container 52 at the level of the valve outlet 6i, or in the immediate vicinity (i.e., a few cm) in a very disturbed zone 76, due to the loss of head generated by the a said valve 6i. P3 is, in the case, for example, sequentially passed from P2 ~ 2 bar to P3 = 1.4 bar, P4 being at atmospheric pressure, or substantially at atmospheric pressure due to output 67.

[0091] In said embodiment, a complementary air inlet 77 was also provided, injected, for example, sequentially with the flocculant by the instrument 78, or even in parallel.

[0092] Emulsion 79 on leaving the flocculant treatment becomes an air emulsion in the thick flocculated sludge.

[0093] The two sections 63 and 66 are, for example, cylindrical of the same diameter d3, for example, equal to the average diameter of the container, for example, d1 + d2 /2.

[0094] For 10 m3/h of slurry, an air flow of 60 Nm3/h minimum, and this regardless of the injection mode, the container having a section of 200 mm for a height of 5 m, 10 m, 30 m or more, a very strong stripping effect (in the Anglo-Saxon language) (pulling off trapped gases) is observed, the air being intimately mixed with the mud.

[0095] With reference to the flocculant, it will be used, preferably, a polymer, for example, cationic.

[0096] Example, for a slurry containing 7 g/l of DM, 50 g of raw polymer are used, for example, prepared with 5 g/l, or an injection of 10 l of solution per m3 of slurry. The injection is made at the immediate exit of the column from the container.

[0097] The sludge is then evacuated, for example, gravitationally via a pipe (not shown) with an outlet in a filter bag (not shown) and the thick sludge being, for it, recovered, for example, by scavenging for constituting thick blocks, of a factor of 50, for example, in relation to the sludge at the entrance (t of DM multiplied by 50 before depletion in the filter bag).

[0098] As a variant, a reagent can be added that improves the shocks between the sludge particles. It can, for example, be used at a height of 10%, 5%, 1% of the DM rate of the sludge as seen above.

[0099] This reagent is, for example, sand, calcium carbonate, burnt lime, etc... it is introduced upstream of the column, for example, in the middle of a mixing vat with the sludge (not registered ).

[0100] Oxidations reagents may also be provided.

[0101] Figure 4 shows a device 80 for treating sludge 81 injected by a pump 82 into an in-line container 83 in an in-line container 83. The container 83 comprises a first zone 84 of small volume (< 50 l) formed by a first chamber 85, for example, parallelepiped or cylindrical, into which, on the one hand, the sludge is injected, for example, in a low part at a flow rate Q, for example, 10 m3/h and, on the other hand, the air compressed or super-pressed 86, from a super-presser 87, at a flow rate Q' (eg 100 Nm3/h), e.g. through two lateral instruments 88 alternately, perpendicular to the sludge flow to form a first air/ mud 89.

[0102] The chamber 85 is, for example, at a pressure P of 5 bar absolute and is connected by a pipe 90 with a section smaller than that of the chamber, for example, in the middle, thus forming a restriction that causes a pressure drop to a second zone 91 formed by a second chamber 92, substantially cylindrical, oblong or tubular, for example, with a larger section than chamber 85, for example, twice the length L1, in which the first emulsion 89 obtained by the air/slurry mixture is at a lower pressure P', for example, 4.5 bar absolute.

[0103] The device comprises a compartment 93 formed of a tube 94 terminated with a degassing chamber 95 provided with mixing means 96.

[0104] The tube 94 comprises a restriction valve 97, allowing to change the pressure in the compartment between its upstream part and its downstream part and is provided with means 98 of injections of a flocculant known per se downstream of restriction 97, to form a second degassed flocculated emulsion 99 in chamber 95.

[0105] The degassing chamber 95 is, for example, a cylindrical reservoir of sufficient volume to evacuate excess air, and gravitationally feeds, through an outlet pipe 100, a concentrating device or capacity 101, which will serve as a float.

[0106] The degassed emulsion 99 reaches the lower intermediate part 102 of the apparatus and immediately separates into solid matter 103 which rises on the surface and into transparent water 104 which is gravitationally evacuated at 105, continuously in a first reservoir 106 of cylindrical shape .

[0107] Solid matter 103 is evacuated in the upper part of the concentrator - float 101, for example, by a narrowed conduit 107 which evacuates solid matter 108 by pumping (pump 109) towards a centrifuge unit 110, with additional decantation in an annex reservoir 111, of the remaining water at 112.

[0108] The reservoir 106 of the apparatus 101 is advantageously of small size (but not necessarily), that is, for example, of a volume corresponding to 1% of the volume of mud conveyed per hour, for example, 100 l for 10 Nm3/ H.

[0109] The reservoir is closed by conduit 107 of reduced or narrowed section, allowing to maintain a slight overpressure above an absolute bar, for example 1.2 bar.

[0110] With the invention, a totally unexpected phenomenon of immediate flotation is produced, with an ascent velocity V in the reservoir from 50 to 250 m/h, much higher than the velocities observed with the previous technique (2 to 20 m/h) .

[0111] According to the invention, there is an extraordinary dynamic flotation effect (which allows notably to predict a small size apparatus).

[0112] For example, a float with a surface of 1 m2 and a total volume of 1 m3 is capable of generating between 10 and 13 m3/h of sludge and 200 to 250 kg/h of DM and leaving a slurry of 80 to 120 g/l MS.

[0113] With the invention, it is possible to leave a thickening E of the mud layer up to more than one meter. The ascent speed of the slurry, accumulated to the porosity of the slurry, also allows to keep the sludge floating for a very long time (several hours if desired and if the reservoir is dimensioned accordingly), which has the effect of allowing the thickening of the mud cake without penalizing the underlying water quality.

[0114] At the time of ascent the mud at a density of 0.6 to 0.9. The porosity is unstable and such that, even after centrifuging at 110, for example, at 3000 T/minute, the slurry retains a porosity that allows it to float on water.

[0115] After having sufficiently thickened the sludge in reservoir 106, and/or in the attached reservoir 111, depending on the needs, it can be extracted by scraping, overflow, continuous pumping or in a batch process (in this case, it is the overflow by conduit which is more particularly described).

[0116] The concentration apparatus can also be a column, a simple or more complex tank equipped with a system for recovering the floats and an overflow as will be described with reference to the following figures.

[0117] It should be noted that, in a batch process, it is also possible to let the sludge thicken in a first apparatus, while another one is filled.

[0118] For a mass load of 200 to 250 kg/h of dry matter, it is possible, for example, to envisage a device with 1 m3 and 1 m of surface.

[0119] The flotation of sludges is, in fact, so effective (it is the size of the bubbles, due to the flocculation on the emulsion, that allows it, compared to a classic float that pressurizes the flotation air and does not allow an ascent rate as strong and a slurry as consistent) as a thick cake is obtained.

[0120] This then forms a kind of mud plug that exits by extrusion through conduit 107, overflowing the settling vessel.

[0121] This surprising effect allows to use a container of small size and capable of working without any moving part, which limits the energy consumption of the set.

[0122] Remember that the classic flotation or thickening systems give results of 30 to 40 g/l maximum, lower by a factor of 3 than what is obtained with the invention.

[0123] The exceptional thickening obtained also quickly, according to an embodiment of the invention can have multiple advantages.

[0124] It allows to concentrate biological sludge in order to reduce the volume that enters digesters.

[0125] It allows to reduce the volume of sludge entering separation devices such as a centrifuge.

[0126] It authorizes the operation of centrifuges and press filters in their optimum performance range and, as a result, greatly improves the siccity of dewatered sludges by at least 5 to 6%, even 10%.

[0127] Improving the siccity, consequence of the previous concentration by the device and/or by the process, according to the invention, also allows to subtract a large part of the unbound water from the matter to dehydrate and reduce the operating times of the devices.

[0128] Figures 5A, 5B and 5C show another embodiment of an effluent treatment device 113, according to the invention.

[0129] The device 113 comprises a slurry feed, through a pipe 114 provided with a regulating valve 115 and a mixer 116, with a cylindrical chamber 117 of small volume (for example, 36 l) in the lower part.

[0130] The chamber 117 is also powered by two instruments 118 supplying compressed air. It is connected at the top to a second chamber 119, via a joining pipe 120, said second chamber being cylindrical and of volume, for example, 500 l. It is terminated, at the top, by a tubular compartment 121 provided with a venturi 122, to the outlet of which means 123 for feeding flocculant are connected. The tubular compartment 121 forms a curve and feeds, at the top, a degassing apparatus or chamber 124, open at 125 at atmospheric pressure and connected, at the lower part, 126, for example, frusto-conical, via a gravity feed pipe 127, to the capacity or concentrator device 128.

[0131] The concentrating apparatus 128 will be described more precisely with reference to figures 7A to 7C. It comprises, in addition to its supply, in the lower part 129, by the flocculated emulsion coming from the degassing apparatus 124, an outlet pipe 130 for the thick sludge and an outlet pipe 131 for the transparent water obtained.

[0132] In fact, the concentrator apparatus, according to the embodiment of the invention described here, does not act as a classic float as the reactor pressure is not high enough and, as a consequence, the size of the air bubbles does not it lies in the micrometric but millimetric domain.

[0133] This property gives the mud a remarkable upward speed.

[0134] The observed ascent speed is then estimated to be greater than 50 m/h, and may reach 100 m/h, even 200 m/h.

[0135] The device, according to the embodiment of the invention, more particularly described here will allow to concentrate the digested sludge at the exit of the digester, suitable to be then stored in a reservoir with agitated sludge, before centrifugation.

[0136] This setting allows you to obtain: • better sicity at the centrifuge outlet (exceeding 30%); • a two-odor limitation: long-term storage (greater than 4 weeks) of concentrated sludge showed an absence of odors (H2S and NH3); • the possibility of using centrifuges with lower flow and lower cost.

[0137] In addition to a very sensitive reduction in the size of concentration tools, typically static or mechanical thickeners (with much higher performance and a consequent absence of odors), the invention therefore opens up perspectives for reducing the size of filtration instruments ( centrifuge), limiting investments.

[0138] The following are examples of lines and results on biological sludge obtained with a device, as described with reference to figures 4 and 5.

[0139] Example #1: Sludge characteristics: • Sludge consists of primary sludge and biostyr washing sludge (addition of FeCl3 and multi-wire input polymer); • they have a siccity in the order of 35 g/l - 40 g/l; • sludge no longer settles over time.

[0140] Results after application of the invention: • The polymer Praestol 860 BS added in the state, at the rate of 1 kg/t of DM; • siccity: 85 g/l.

[0141] These results show that it is possible to concentrate the digested sludge from the inlet of the digester by 50%, thus allowing: • to significantly increase the digester load by adding third-party sludge; • increase the production of biogas and favor an economically viable placement on the network (in addition to being sustainable development); • improve the operation of the centrifuge, which would work in its optimum performance range.

[0142] The invention thus makes it possible to obtain remarkable sludge concentration performances from 80 g/l to 100 g/l.

[0143] The device used is, moreover, very compact.

[0144] Thus, a device that allows treating 15 m3/h of sludge has an interior soil volume of 10 m2 - a device of 50 m3/h will not exceed 20 m2.

[0145] Example 2: • Sludge characteristics.

[0146] These are MBR (Biological Reactor Membrane) sludges.

TABELA 2

Vazão lama média = 11,73 M3/h MS LAMA = 15,8 g/l na entrada Vazão polímero = 635 l/h a 3,5 g/l Ar = 57 Nm3/h Pressão P interna ao recipiente = 0,88 bar relativo TABELA 3

[0147] The invention here shows performances that can reach 90 g/l, from a slurry at 40 g/l. TABLE 1

TABLE 2

Average sludge flow rate = 11.73 M3/h MS SLUDGE = 15.8 g/l at the inlet Polymer flow = 635 l/h 3.5 g/l Air = 57 Nm3/h Pressure P inside the vessel = 0.88 bar relative TABLE 3

[0148] Figure 6 shows another embodiment of a container 131 according to the invention.

[0149] The first zone 132 of small volume here is the central part 133 of a venturi 134 formed on the slurry feed pipe 135, the air injections being made by two symmetrical pipes 136, injecting in the direction of flow, for example , with an angle α between 20° and 90°, for example, 30° via frusto-conical narrowings 137, which touch on the central part 133.

[0150] The second zone 138 of the container is, in this case, formed by a pipe part 139 of the slurry feed pipe 135, connected, for example, through a diaphragm 140 to regulate the pressure P, to a cylindrical chamber 141 of larger diameter, for example, 10 times the diameter of pipe 135, the set of first and second zones extend over a length L, for example, of 1 m, before the exit of the emulsion obtained over chamber 141, via a coupling instrument with a valve or another type of valve (not shown).

[0151] Figures 7A to 7C show the concentrator device 128 of figure 5.

[0152] This comprises a cylindrical tank 128 equipped with an emulsion inlet by pipe 127, arched, centered inside the tank at a level corresponding to one third of the height of the tank.

[0153] The pipe is curved at 90o and ends with an outlet in a funnel 152 widened upwards, to allow the rise of the sludge bubbles 153 that constitute a layer 154 of height h adjustable, depending on the flow.

[0154] The slurry rises in the vat at a speed of the order of 50 m/s and pours into a central 155 conical funnel.

[0155] The top face 156 of the bowl is inverted cone open at its center 157 to let the air release and allow a slurry compression at 158 between the inner face 159 of the inverted cone and the upper edge 160 of the funnel periphery.

[0156] The slurry is then poured into the funnel and is evacuated at the bottom by gravity via an arcuate tube 161 terminated by a pipe 130.

[0157] The clear water 162 is, as for it, evacuated in the lower part 163 of the tank via a vertical tube 164, allowing the siphoning (arrow 165) and the exit in the upper part by pipe 131.

[0158] Shown in figures 8A and 8B is another embodiment of concentrator apparatus 166 usable, according to a variant of the invention.

[0159] It comprises a cylindrical vessel 167 fed with mud 168 from above via a pipe 169 which dips into and is centered with its end 169, for example, situated one third or a quarter of the height of the vessel.

[0160] A diversion plate 170 allows the mud to rise at high speed to form a mud plug 171 that exits in the upper part 172 of the tank, comprising an outlet end 173 in the shape of a frustum of cone, the mud evacuating itself by a spillway along the peripheral edge 174 in a peripheral annular reservoir 175, then via an outlet pipe 176 in the lower part of said annular reservoir.

[0161] The water 177 that remains in the lower part is in terms of it evacuated via an outlet turbulence 178.

[0162] Here it is still possible to regulate the height of the mud layer and, therefore, its accumulation and its siccity via the regulation of the flow rates and the nominal dimensions of the tank elements.

[0163] Figure 9 shows another embodiment of a concentrating apparatus 180 formed by a parallelepiped tub 181 provided at its center with an inner chamber 182 also parallelepiped, defining a space 183 between the inner walls of the tub 181 and the outer chamber of the chamber 182.

[0164] The mud arrives in the middle part 184 of the chamber, rises by flotation, creating a mud plug of constant thickness and spills over the periphery 185 of the chamber in the annular peripheral part 183 between the walls of the chamber and the well.

[0165] It is retrieved through cut flaps 186, for example, at 30° and evacuated at 187 at the bottom through a collector bottom 189, for example, in the form of a prism.

[0166] The water is, as for it, evacuated in 189, through an exit orifice located in the upper part of a vertical collecting channel 190, functioning as a column of siphon water.

[0167] As is evident and as also results from the foregoing, the present invention is not limited to the embodiments more particularly described. On the contrary, it encompasses all the variants, especially those in which several devices are used one after the other.

Claims (35)

1. Process for treating and processing sludge (2, 31), in which a first emulsion (14, 57, 89) of sludge is created in a container (5, 6, 33, 52, 83, 117, 119, 131 ) in a pressurized line fed with the slurry continuously at a first flow rate Q (m3/h), by collision of the slurry (2, 31, 81) with the air (13) injected into the container (5) at a flow rate Q' (Nm3 /h), where Q' > 5Q, the evacuation of said first emulsion is carried out at the outlet of the container via an element (18, 38, 61) that generates a loss of pressure, then the filtration or decantation of the materials into suspension of the obtained emulsion (23) is carried out by separating them from the liquid part (27, 49, 105, 112) which is continuously emptied, said process being characterized by the fact that, to create said first emulsion by mud collision with the air, the slurry (2) and the air (13) are injected into a first zone (8, 56, 84, 117, 133) of the container, and the formed emulsion is evacuated to a second zone (16, 59, 91, 119, 141) of the container that extends over a first determined length L1, wherein the injection of air and slurry into the first zone and the length L1 are suitable to form said first emulsion formed from droplets of slurry in the air, then, said evacuation of the first emulsion of the container is realized, via the element that generates a pressure drop in a tubular compartment (19, 43, 62, 121) which extends over a second determined length L2, in which at least one flocculant (22, 45, 73, 98 123) is injected, to obtain in said compartment a second air emulsion in the coagulated and flocculated sludge, and said second emulsion is at least partially degassed (20, 46, 67) by ventilation (20) of the compartment, before the said filtration (25, 25') or decantation. 2. Process according to claim 1, characterized in that the first zone has a small volume of less than 0.05 m3. 3. Process according to claim 1 or 2, characterized in that the first determined length L1 is greater than 50 cm. 4. Process according to claim 3, characterized in that the second determined length L2 is greater than 1 m. 5. Process according to any one of claims 1 to 4, characterized in that the mean pressure P in the container (5, 33) is such that 150 kPa (1.5 bar) < P < 1000 kPa (10 bar) ) and Q' is such that 10 Q < Q' < 100 Q. 6. Process according to any one of claims 1 to 5, characterized in that the emulsion is substantially degassed at the outlet of the container, inside a degassing chamber (95, 124) provided with stirring means (96) . 7. Process according to any one of claims 1 to 6, characterized in that the in-line container (8) is a column (6) of average diameter and height H > 10 d, the slurry (2) is introduced in the lower part (10) of the column in the gaseous layer created by the air injected at the level of said slurry feed. 8. Process according to claim 7, characterized in that the sludge (2) in the column (6) is sprayed on a wall (11) or an inner screen of the container to improve its break in the gaseous flow. 9. Process according to any one of claims 1 to 8, characterized in that the mud (2) is introduced into the lower part (10) of the container (5, 6) via a static mixer. 10. Process according to any one of claims 1 to 9, characterized in that the flocculant (22, 45, 73) is a polymer injected into the immediate exit of the container, before ventilation. 11. Process according to any one of claims 1 to 10, characterized in that at least one reagent selected from sand, calcium carbonate, burnt lime, oxidation reagents and/or coagulation auxiliary reagents, is introduced upstream of the container (6) in the mud flow. 12. Process according to any one of claims 1 to 11, characterized in that at least one reagent selected from sand, calcium carbonate, burnt lime, oxidation reagents and/or coagulation auxiliary reagents, is introduced downstream of the container. 13. Process according to any one of claims 1 to 12, characterized in that the compartment (19, 62, 94) is tubular and has an average flow cross section equivalent to that of the container. 14. Process according to claim 13, characterized in that the compartment comprises at least one element (18, 61, 97), which generates a pressure drop downstream of the outlet of the container (6, 52), at outlet from which the flocculant is injected. 15. Process according to claim 14, characterized in that the compartment comprises at least a second element, which generates a pressure drop before the first generating element, at the outlet of which at least one reactant and/or air is introduced. 16. Process according to any one of claims 1 to 15, characterized in that the element or elements that generate pressure drop is/are Venturi tubes (18, 38, 44, 64). 17. Process according to any one of claims 1 to 16, characterized in that a rapid and/or substantially instantaneous concentration of the sludge is carried out by flotation/accumulation of the flocculated emulsion in a capacity (101, 128, 166, 180 ), which acts as a concentrator. 18. Process according to claim 17, characterized in that the sludge is evacuated by overflow from the concentrator. 19. Process according to any one of claims 1 to 18, characterized in that a treatment of the sludge downstream of the compartment is carried out by centrifugation, filtration and/or pressing. 20. Process according to any one of claims 1 to 19, characterized in that the injected air is heated and/or mixed with water vapor. 21. Process according to any one of claims 1 to 20, characterized in that air is injected to form a helical flow in the mud flow. 22. Device for treating and processing sludge comprising: an in-line container (5, 6, 33, 52, 83, 117, 119, 131), means (3, 82) for continuously feeding said container with sludge (2, 31) at a first flow rate Q (m3/h), means (87) of feeding said container with air at a flow rate Q'(Nm3/h), where Q' > 5Q, and means (25, 25', 68) filtering and/or decanting the flocculated emulsion, adjusted to separate the liquid part from the suspended matter and recover it continuously, said device being characterized by the fact that: the means (3, 82) of feeding the container with slurry and with air are adjusted to inject the slurry and air into a first zone of the container, then to transport the mixture in a first length L1 to form a first emulsion of airborne mud droplets, wherein the device comprises a compartment (19, 39, 62, 93, 121) of evacuation of the first emulsion obtained in the container via an element (18, 38, 61) that generates a loss. loading, in which the compartment (19, 39, 62) is tubular and extends over a determined length L2, comprising ventilation means and means (21, 72, 98, 123) for injecting at least one flocculant (22 , 45, 73) in said tubular compartment upstream with respect to said vent, so as to form a second air emulsion in the coagulated and flocculated sludge. 23. Device according to claim 22, characterized in that the first zone of the container has a small volume of less than 0.05 m3 confined between two flow walls. 24. Device according to claim 22 or 23, characterized in that the container (5, 33, 52) in line is a column (6) of average diameter of height H > 10 d, in which the slurry is introduced in the lower part (10) of the column in the gaseous layer created by the air injected at the level of said slurry feed. 25. Device according to claim 24, characterized in that the column (6) further comprises an internal screen arranged at the outlet of the injection means in the column, for breaking the mud jet. 26. Device according to any one of claims 22 to 25, characterized in that it comprises a static mixer for the sludge upstream of the container. 27. Device according to any one of claims 22 to 26, characterized in that the compartment (19, 62, 94) is tubular with a cross section of the average flow equivalent to that of the container. 28. Device according to claim 27, characterized in that the tubular compartment (16) comprises at least one element (18, 44, 61, 97) that generates a pressure drop downstream of the outlet of the container, at the exit from which the flocculant is injected. 29. Device according to claim 28, characterized in that the tubular compartment comprises at least one second element (38) that generates a pressure drop before the first generator element, at the output of which at least one reactant and/ or air is introduced (42). 30. Device according to any one of claims 28 and 29, characterized in that the elements that generate pressure drop are Venturi tubes. 31. Device according to any one of claims 22 to 30, characterized in that it further comprises a degassing chamber (95, 124) downstream of the container provided with stirring means (96). 32. Device according to any one of claims 22 to 31, characterized in that it further comprises a capacity (101, 128, 166, 180) downstream of the compartment that plays the role of a concentrator, adjusted to allow the flotation of the mud flocculated at a certain height. 33. Device according to claim 32, characterized in that the volume comprises means (107; 159, 160; 173, 174) for evacuating the sludge by overflowing. 34. Solidified organic sludge cake, obtained by the process as defined in any one of claims 1 to 21, characterized in that it is formed from an organic sludge and has a volumetric mass between 0.5 and 0.9 g /cm3. 35. Organic mud cake, according to claim 34, characterized in that it has a porosity equal to 85% + 5%.

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